You're welcome I know how it feels to have to worry about all this stuff so I wanted to try to help. The 8% form submit you are seeing is outside one Standard Deviation so it appears a bit abnormal. When you figure in all those other points check to see if it is still outside of one SD or maybe even outside two Standard Deviations which I suspect it will be. It doesn't necessarily mean something has to be wrong but it suggests so. It could be CCBill, a slow loading form, hosting problems, error on the site, influx of abnormally horrible traffic, many things but it suggests something is up somewhere.
Here is a visualization of Standard Deviation which might help. It's not using your exact data but is just from Wikipedia.
The dark blue areas (labeled 34.1%) are what I call "normal". That is one Standard Deviation from the mean which is the center. 70% on average will fall within this.
The light blue areas (labeled 13.6%) are what I call "somewhat normal". That is two standard deviations. 95% on average will fall within this area statistically.
When you start seeing values outside the dark blue and light blue areas then there is likely a problem somewhere. If you suddenly start seeing a pattern recurring of months outside these areas then that would be very abnormal and suggest something has changed somewhere. This is one way to find abnormalities statistically in a proven way.
If you were to enter all the monthly data in for the last couple years then you'll get a completely different set of standard deviations and ranges than I have here and your data would be much more accurate with 36 - 60 months instead of my mere 5.